Megadineura Malaise

Wei, Meicai & Nie, Haiyan, 2008, A new species of Megadineura Malaise (Hymenoptera: Tenthredinidae) and a key to the known species of the genus, Zootaxa 1920, pp. 51-60 : 52-53

Megadineura Malaise

Megadineura Malaise, 1931 , Ent. Tidskr., 51: 147.

Stenomesoneura Wei, 1998, Acta Zootaxonomica Sinica, 23(4): 411. Nomen nudum.

Type species: Dineura grandis André, 1882 . By original designation.

Description: Body medium-sized, elongated; head distinctly narrower than thorax. Mandibles similar to Nematus , in lateral view narrowing from swollen base to thin blade-like apex; malar space linear; clypeus not very narrow, shallowly incised in anterior margin; eyes large with inner margins slightly curved, weakly convergent downwards, shortest distance between eyes slightly longer than height of eye; upper hind orbit narrow, about 1/4–1/5 length of eye; distance between antennal sockets about half width of inner orbit, frontal crest in lateral view angularly produced between antennal sockets; middle fovea very deep, lateral foveae open below; anterior wall curved, high and strong, extending to but not touching eyes laterally; postocellar area transverse, more than 2 times as broad as long; gena narrow with shallow and narrow orbital groove, occipital carina absent; palpi short, 5th palpimere of maxillary palp shorter than width of 3rd antennomere. Antennae long and thick, not tapering toward apex, about as long as thorax and abdomen together, about 4 times the width of the head, scape and pedicle broader than long, 3rd antennomere distinctly shorter than 4th antennomere. Prescutum more than 2 times as long as broad; anterior furrow of mesoscutellum narrow, deep, roundly curved, mesoscutellum flat, post-tergite small; cenchri small and round, ratio of distance between them and diameter of a cenchrus about 1–2; epicnemium feebly elevated, almost flat, divided from mesepisternum by a fine furrow; mesepisternum evenly pilose, without naked stripe, anterior margin with a fine carina; metepimeron large. Inner tibial spur of foreleg with distinct membrane, apex slightly furcated; hind tibia longer than hind tarsus as 5: 4, outer side of tibia with a long, deep furrow; hind basitarsus about as long as following 3 tarsomeres together, 4th tarsomere longer than broad; claw elongate, without basal lobe, inner tooth close to but shorter than apical tooth. Wings long, narrow, apex of vein C weakly swollen, Sc basad of vein M, R+M distinctly shorter or slightly longer than first abscissa of vein M, cu-a joining cell 1M at or slightly beyond middle, both 1m-cu and 2m-cu joining cell 1Rs, 2r joining cell 2Rs basad of middle, remote from; cell 1Rs as long as or slightly longer than 2Rs, 2Rs more than 2 times longer than broad, 2M longer than broad, basal anal cell open, vein 2A+3A straight. Hind wing with cells Rs and M closed, petiole of anal cell 1A shorter than cu-a, cu-a strongly oblique outwards. Abdomen two times the length of the head and thorax together, first tergite distinctly incised posteriorly and with a small blotch, 8th–9th tergites normal without middle carina, not enlarged, cerci long, slender. Upper part of mesepisternum densely and coarsely rugose, abdominal tergites densely microsculptured. Ovipositor about 2 times the length of the hind basitarsus; sheath simple, strongly tapering toward apex in dorsal view; lancet simple, without ctenidium and thick spines, most annular sutures with one row of very short annular spines, serrulae with fine subbasal teeth; penis valve with a ventral tooth, dorsal lobe not curved.

Systematic position: Megadineura Malaise is a member of the tribe Mesoneurini (Wei, 1998; Zombori, 1982). It is similar to Mesoneura Hartig, 1837 and Renonerva Wei & Nie, 1998. Mesoneura differs from Megadineura in its short and robust body; antennae much shorter than thorax and abdomen together, less than twice as long as width of head; vein 2r and 2m-cu interstitial to vein 1r-m, petiole of cell 1A in hind wing longer than cu-a and mesepisternum not reticulate with anterior margin smooth, without a distinct carina.

Renonerva Wei & Nie, 1998 differs from Megadineura in having a robust body, abdomen as long as head and thorax together; eyes very small, shortest distance between eyes more than 2 times height of eye; upper hind orbit longer than height of eye, gena very broad; malar space 2 times diameter of ocellus; epicnemium strongly elevated, separated from mesepisternum by deep and broad furrow; vein 2r in fore wing interstitial with vein 1r-m, cell 2Rs about 1/2 length of 1Rs; petiole of cell 1A in hind wing not shorter than vein cu-a; abdominal tergites shining, without distinct microsculpture; ovipositor hardly longer than hind basitarsus.

Togashi (1964) pointed out that Katsujia Togashi, 1964 was similar to Megadineura . However, Katsujia differs from Megadineura in its robust body, the form of the mandibles as in Dineura , short antennae, less than twice as long as width of head, malar space almost as long as diameter of ocellus, hind basitarsus as long as following 2 tarsomeres together and lancet with thick annular spines.

Distribution: E. Asia. Wei & Nie (1997) placed Megadineura under the III10 geographic distribution pattern, i.e. a taxon disjunctively distributing in Himalayas and N. E. Asia. However, the new distribution data of Megadineura show that the distribution pattern of the genus belongs to Pattern III8 of E. Asian element, i.e. a taxon distributing from Mt. Himalayas through Mt. Wuling, Mt. Qinling, Mt. Funiu to N. E. Asia region) ( Wei & Nie 1997).

The known species of Megadineura can be identified using the following key.